Toner dispensing device

ABSTRACT

A toner dispensing device for use in a developing apparatus of a dry-copying process photocopying machine which comprises a toner dispenser casing having a lowermost projecting portion with a slit, a container for toner powder removably received in the casing, a coil spring accommodated in the projecting portion above the slit, means for pulling the spring, means for adjusting the tension of the spring and a driving device for the pulling means. The spring is adapted intermittently to expand by the pulling means so that gaps are formmed between the neighboring turns of the spring for the toner powder to pass through and to contract so as to close the gaps to suspend feeding of toner powder.

United States Patent Tanaka et al.

TONER DISPENSING DEVICE lnventors: Susumu Tanaka; Yuji Enoguchi;

IIidetoshi Kawabata, all of Osaka,

Japan Minolta Camera Kabushiki Kaisha, Osaka 541, Japan Filed: May 20, 1974 Appl. No.: 471,779

[73] Assignee:

[30] Foreign Application Priority Data May 28, i973 Japan 48-62561 References Cited UNlTED STATES PATENTS 9/ I964 Eichorn et al.. 222/406 X 1 June 10, 1975 Primary Examiner-Allen N. Knowles Attorney, Agent, or Firm-Wenderoth, Lind & Ponack [57] ABSTRACT A toner dispensing device for use in a developing apparatus of a dry-copying process photocopying machine which comprises a toner dispenser casing having a lowermost projecting portion with a slit. a container for toner powder removably received in the casing, a coil spring accommodated in the projecting portion above the slit, means for pulling the spring, means for adjusting the tension of the spring and a driving device for the pulling means. The spring is adapted intermittently to expand by the pulling means so that gaps are formmed between the neighboring turns of the spring for the toner powder to pass through and to contract so as to close the gaps to suspend feeding of toner powder.

6 Claims, 5 Drawing Figures PATENTEDJUN l 0 ms SHEET FIG! FIG. 2

SEEET PATENTEDJUN l 0 1915 FIG. 3

FIG 5 1 TONER DISPENSING DEVICE The present invention relates to a dry-copying process photo-copying apparatus, and more particularly to a unitary toner dispensing device for use therein.

Commonly, in photographic copying by xerographic or similar techniques, subsequent to projection of a light image of an original to be copied onto a charged photosensitive photoreceptor surface to form an electrostatic latent image thereon, the latent image is developed at a developing station by developing material comprising magntizable carrier material and electro seopic toner powder to produce an electroscopic toner powder image in the configuration of the latent image on the photoreceptor surface for tansfer onto a copy paper sheet so as to obtain a copy of the original image thereon. After completion of the transfer, the used developing material scraped off a developing roller in preparation for subsequent copying must be replenished with fresh toner powder from the toner dispenser to maintain a fixed toner concentration, since the toner powder in the developing material is gradually exhausted by the repeated developings, which results in inferior development due to low toner concentration in the developing material.

Conventionally, a toner dispensing device has been proposed which comprises a rotary member such as a roller or a brush accommodated at the bottom portion of the toner dispenser casing so as to be driven by a motor, and a slit of a fixed width formed at said bottom portion immediately below the rotary member, with the rotary member adapted to rub against the slit at speeds of rotation variable depending upon requirements, by controlling voltage to be applied to the DC motor, thus enabling a desired amount of toner powder to be supplied to the developer material through the slit.

However, in the above conventional toner dispenser, when the voltage applied to the motor for rotating the rotary member is lowered so as to reduce the rotational speed of the rotary member, for example, to approximately 5 to 6 r.p.m., the driving torque itself is also lowered, which fact, together with the arrangement that part of the rotary member is in contact with the dispenser casing, tends to hinder uniform and smooth r0- tation of the rotary member, consequently resulting in uneven amount of toner power to be supplied to the developer material. Particularly, if the rotary member is so designed that the most part the thereof is in contact with the inner wall of the dispenser casing, smooth rotation of the rotary member is further obstructed.

According to a conventional toner dispensing device, a motor with larger driving force is employed to over come the above inconvenience, which is also disadvantageous due to resultant larger size of the apparatus and higher cost for manufacturing. Similarly, some conventional devices adopt a constant speed for the rotary member with variable slit widths for supplying desired amount of toner powder, but such devices also have such disadvantages that, if the width of the slit is adjusted to be too narrow, clogging of the slit with the toner powder may result, making it impossible to feed proper amount of toner powder smoothly with adjustment of the slit width complicated.

Accordingly, an essential object of the present invention is to provide a toner dispensing device which is accurate in functioning for uniform and positive replenishment of toner powder wherein the amount of toner powder to be fed is readily adjustable with substatial elimination of the disadvantages inherent in the conventional toner dispensing devices.

Another important object of the present invention is to provide a toner dispensing device of the above de scribed type which is simple in construction and compact in size.

A still further object of the present invention is to provide a toner dispensing device of the above described type which can be produced at low cost and is easy of maintenance.

According to a preferred embodiment of the present invention, the toner dispensing device comprises a dispenser casing retained in an opening formed on the top wall of a developer housing immediately above a stirrer in the developing device with the casing having a projecting portion of semi-circular cross section at the lower part of said casing, which lower part is provided with a slit at the extreme lower portion thereof for the toner powder to pass therethrough, a container for storing the toner powder removably received in and in communication with the casing, a coil spring with neighboring turns thereof contacting with each other in the normal contracted state of the spring, which spring is accommodated in the lower part of the casing immediately above the slit, means of pulling one end of the spring with the other end of the spring connected to means for adjusting the tension of the spring and a driving device for the pulling means.

The pulling means further includes a slidable plate which is slidably mounted on a guide plate secured to one side wall of the developer housing and which is provided with a rack in the undersurface thereof, a cable line with one end fixed to the slidable plate and the other end thereof connected to one end of the spring through a pulley. The rotation of a motor of the driving device is transmitted, through a chain and a plurality of sprokets and gears, to a special gear having a toothed portion and a toothless portion, the toothed portion of which is adapted to engage the rack of the slidable plate. The other end of the spring is connected, by a cable line, to an adjusting knob of the tensioin adjusting means through a pulley, which knob is adapted to adjust the tension of the spring in its contracted state to such an extent that the neighboring turns of the spring remain contacting with each other so as not to pass the toner powder therethrough.

Upon rotation of the motor, the slidable plate which is in engagement with the toothed portion of the special gear is moved in the direction to pull the spring, thereby forming gaps between neighboring turns of the coil spring for the toner powder to pass therethrough. When the toothless portion of the gear reaches the rack, the engagement therebetween is released and the slidable plate immedately returns to its original position with the gaps between the neighboring turns of the spring again closed, consequently feeding of the toner powder being suspended.

As is seen from the above, according to the device of the present invention, toner powder can be fed uniformly and positively by simply expanding or contracting the spring with the amount of the toner powder to be fed easily controlled by adjusting the tension adjusting means.

These and other objects and features of the present invention will become apparent from the following description taken in conjunction with the preferred em- 3 bodirnent thereof with reference to the accompanying drawings. in which;

FIG. 1 is a schematic cross sectional view of a toner dispensing device according to an embodiment of the present invention,

FIG. 2 is a rear elevational view partly in section of the device shown in FIG. I,

FIG. 3 is a perspective view showing mechanism associated with a pulling means employed in the device in FIG. I,

FIG. 4 is a side clcvational view, on an enlarged scale, of a rack and gears associated therewith employed in the device in FIG. 3, and

FIG. 5 is a perspective view showing mechanism associated with a tension adjusting means of the device in FIGv 1.

Before the description of the present invention proceeds, it is to be noted that like parts are designated by like numerals throughout the several views of the ac companying drawings.

Referring to HQ. 1, there is shown a toner dispensing device A according to the present invention as applied to an electrostatic latent image developing device D of :1 copying apparatus The housing 7 of the developing device D extends the width of a known photoreceptor drum l0 driven by a conventional means and is provided with an opening C adjacent to a photoreceptor surface of the drum l0 whcreat development of a latent image formed on the surface 10' is effected and another opening 7e in which the toner dispenser A is received for replenishing toner powder depleted from developing material during development of the latent image. There is provided a sump 7c for storing developing material 9 comprising magnetizable carrier material and electroscopic toner particles at a lowermost portion of the developer housing 7. The developer housing 7 is disposed adjacent to the photoreceptor surface 10' and suitably secured to the frames of the copying appa ratus (not shown). The toner powder dispenser A is retained by the edge 7fof the opening 7e which is formed on the top wall 7d of the developer housing 7 adjacent to the rear end thereof remote from the opening C.

The developer housing 7 includes a magnetic roller 1 adjacent to thc photoreceptor surface 10' which roller 1 comprises an outer cylinder 2 of a nonmagnetic material. such as aluminum or brass, extending the width of the developer housing 7 and having minute concave and cover portions formed on the outer periphery thereof for better friction. and three elongated bar magnets 4 which are housed in the cylinder 2 and extend nearly the full length of the latter. The bar magnets 4 are fixedly mounted on a bar 3 which is appropriately secured to the side walls 70: and 7b of the housing 7 (not shown) with the magnets 4 arranged in such positions that the magnetic force fields thereof intersect to form magnetic brush bristles of the developing material on the surface of the outer cylinder 2, which outer cylinder 2 of nonmagnetic material is mounted for rotation about a shaft 5 by means of suitable bearing surfaces carried by side frames of the housing 7 (not shown), so that. upon rotation of the outer cylinder 2 around the stationary elongated bar magnets 4, the magnetic force fields of the latter project through the wall of the outer cylinder 2 to form the developing ma terial pooled on the sump 7c into magnetic brush bris tles on the outer periphery of the cylinder 2. The magnetic brush bristles thus formed are adapted to rub i slightly against the photoreceptor surface it) as the latter rotates counterclockwise in FIG. 1 to visualize the latent image formed on the surface 10.

The developing device D is further provided, in the housing 7 thereof below the toner dispenser A, with a rotary stirrer ll formed by suitably securing a plurality of vanes 13 tangentially on the outer periphery of a shaft 12, which shaft 12 is rotatably supported in the side walls 7a and 7b by bearings 14a and I4!) (FIGSv 3 and 5) The rotary stirrer II which rotates in the direction of the arrow in FIG. I is adapted, during rotation thereof, to mix fresh toner powder cascaded thcreover from the dispenser A with the used developer material of low toner concentration scraped off the cyilindcr 2 by a scraper 6 so as to keep the toner concentration in the developing material 9 pooled in the sump 7c at a uniform level.

Referring now to FICJSv 2 through to 5 the toner dispenser A of the present invention disposed above the stirrer 11 as described above mainly comprises a casing l5 of a trough shape retained in the edge 7f of the opening of the dispenser housing 7 and is provided with a small downwardly projecting portion 16 of a semi-circular cross section having a slit 17 at the lowermost portion thereof which faces the stirrer 11, a container 18 of rectangular cross section which removably fits into the edge 15' of the casing 15 which is in communication with the former. a coil spring 20 with its turns contacting with one another in the contracted state of the spring 20, which spring 20 is received above the slit 17. in the small projecting portion 16 of the easing 15, means 24 for pulling one end of the spring 20 by a driving device 32 provided on the side wall 7a of the housing 7 and means 43 for adjusting the tension of the spring 20 which is mounted on the opposite side wall 712.

The spring 20 is received in the projecting portion 16 of the casing 15 in such a manner that it can be ex panded or contracted without obstruction therein with one end thereof connected to the pulling means 24 through a cable line 21a and with the other end thereof connected to the tension adjusting means 43 through a cable line 21b.

It should be noted here that. in the state where no tension is applied to the spring 20, neighboring turns of the spring 20 are adapted to closely contact to one another without any gap between the outer periphery of the spring 20 and the inner face of the projecting portion 16, consequently toner powder 19 contained in the container 18 being prevented from falling through the slit 17 formed in the direction parallel to that of expansion of the spring 20.

When the spring 20 is expanded by the pulling means 24, the toner powder 19 is adapted to be cascaded over the stirrer 1] through the gaps formed between neigh boring turns of the spring 20, and through the slit 17.

The pulling means 24 mounted on the side wall 70 of the developer housing 7 further comprises a guide plate 25 ofl shaped cross section which has a guide portion 26 provided at its outer face and is suitably fixed to the wall 7a at the base 25' thereof, a slidable plate 24 having a T shaped groove 27' formed in the undersurface thereof which groove 27 is slid-ably titted into the corresponding guide portion 26 of similar T shape of the guide plate 25, the cable line 21:: one end of which is secured to the slidable plate 24 by a set screw 28 with the other end thereof connected to one end of the spring through a pulley 23a rotatably mounted on a bracket 22a fixed on the wall 7a, and the driving device 32 with associated mechanisms described below.

A rack 29 (FIG. 4) is cut in the under-surface of the slidable plate 27 which rack 29 is adapted to engage a gear 41 with a toothless portion 42. An elongated slot 30 is formed in the outer face of the slidable plate 27 in the direction parallel to the movement of the plate 27, while a stopping pin 31 which extends outwardly at right angles from the surface of the guide portion 26 of the guide plate is adapted to project into the slot to limit the movement of the plate 27 toward the left due to tension of the spring 20.

In the driving device 32, a sprocket 35 fixed to a driving shaft 34 of a motor 33 is connected to a sprocket 36 rotatably mounted on the side wall 7 by a chain 37 through sprockets 36X, 36Y and 36Z which are also rotatably mounted on the wall 7, while a gear 38 integrally fixed to the sprocket 36 is adapted to engage, through an idle gear 39, with a gear 40 integrally fixed to the gear 41 having a toothless portion 42 which gear 41 is also rotatably mounted on the wall 7. Consequently, the turning force of the motor 33 is transmitted to the gear 41 through the chain 37, the sprocket 36, and the gears 38, 39 and 40. On the other hand, since the toothed portion 41' of the gear 41 engages the rack 29 of the slidable plate 27, the plate 27 slides rightward in FIG. 3 as the gear 41 rotates clockwise, thus expanding the spring 20. When the toothless portion 42 of the gear 41 reaches the rack 29 as the gear 41 rotates, the engagement between the two is released and the slidable plate 27 is immediately returned to the original position by the tension of the spring 20.

The tension adjusting means 43 which is mounted on the side opposite to the tension means 24, namely, on the side wall 7b of the developer housing 7 has a adjusting knob 48, which is slideable and fixable for positioning in an elongated slot 46 formed in an adjusting plate 44 of rectangular shape with scales 45 graduated along the long side edge of the plate 44. The end of the cable line 21b whose other end is fixed to the other end of the spring 20 is fixed to the adjusting knob 48 through a slot 47 formed in the short side edge of the plate 44 and in communication with the longated slot 46. The intermediate portion of the cable line 21b is passed over a pulley 23b rotatably mounted on a bracket 22b secured to the side wall 7b. Accordingly, by sliding the regulating knob 48 right and left along the slot 46, the tension of the spring 20 in the contracted state thereof varies accordingly, whereby the gaps between the neighboring turns of the spring 20 vary as the slidable plate 27 slide along the guide portion 26 of the gide plate 25 so as to regulate the feeding amount of the toner 19 through the slit 17. A maximum tension to be applied to the spring at its contracted state is required to be within such a range that the spring 20 is not expanded more than necessary without forming gaps between neighboring turns thereof through which toner powder may pass.

In the above device of the present invention, upon rotation of the motor 33, the spring 20 is adapted to expand and contract intermittently as described hereinabove to replenish the toner powder 19 via the slit 17 into the developing material 9 in the sump 7c through the gaps formed between neighboring turns of the spring 20 upon expansion of said spring 20. In this case, the toner powder 19 falling by its own weight falls more positively due to vibrations of the spring 20 caused upon returning of the slidable plate 27 to its original position. it is particularly effective in cases where the toner powder 19 is packed under pressure in the container l8.

Adjustment of the toner feeding amount can be made by varying the number of revolution of the driving means 32 and also by adjusting the tension adjusting means 43. Namely, the number of expansion and contraction of the spring 20 per unit time is increased or decreased through variation of the number of revolution of the above driving device 32.

As is clear from the above description, the toner dispensing device of the present invention is of simple construction wherein the coil spring whose neighboring turns normally contact with each other is accommodated at the bottom portion immediately above the slit of the toner dispenser casing and is adapted to expand and contract intermittently by the driving device. the toner powder being adapted to fall through the gaps formed between the neighboring turns of the spring upon expansion thereof and through the slit in the dispenser casing.

If constant tension is applied to the spring. gaps of fixed intervals are formed intermittently between the neighboring turns of the spring. which makes it possible to replenish the toner powder uniformly and positively.

Furthermore since the toner feeding amount can be regulated readily by adjusting the tension adjusting means or by varying the number of revolution of the driving means, such inconveniences as clogging of the slit with the toner powder due to excessive throttling of the slit opening experienced in the prior art is prevented so long as the width of the slit is formed in advance to such a width as the clogging with the toner powder may not be caused.

Although the present invention has been fully described by way of example with reference to the attached drawings. it is to be noted that various changes and modification are apparent to those skilled in the art. Therefore, unless otherwise such changes and modifications depart from the scope of the present invention, they should be construed as included therein.

What is claimed is:

1. In a toner dispensing device for use in a developing apparatus of an electrostatic copying machine which comprises a dispenser casing retained in an opening formed on a wall of said developing apparatus, said dispensing casing having a slit formed in a bottom portion thereof, a container for toner powder removably received in and communicating with said dispenser casing, and a coil spring provided at the bottom of said dispenser casing above said slit with neighboring turns of said spring adapted to contact with each other in the contracted state of said spring, an improvement thereof for feeding toner powder uniformly and positively which comprises means for pulling one end of said spring for expansion thereof so that gaps are formed between said neighboring turns of said spring for toner powder to pass through said gaps and said slit. said pulling means being adapted to release pulling intermittently so as to allow said spring to be contracted with said neighboring turns thereof closed in order to suspend feeding of toner powder.

2. A toner dispensing device as claimed in claim 1, wherein further comprises means for adjusting tension of said spring for adjusting intervals of gaps between said neighboring turns of said spring when said spring is pulled by said pulling means. and a driving device for said pulling means.

3. A toner dispensing device as claimed in claim 1, wherein said pulling means further comprises a slidable plate slidably, reciprocatingly mounted on a guide plate fixed on a side wall of said developing apparatus, said slidable plate being provided with a rack which engages a special gear having a toothed portion and a toothless portion and which is driven by said driving device. and a cable line secured, at one end thereof, to said slidable plate with the other end of said cable line fixedly connected to said one end of said spring.

4. A toner dispensing device as claimed in claim 1, wherein said tension adjusting means further comprises an adjusting plate with an elongated slot formed therein, and a knob which is slidable in said elongated slot and which can be fixed at desired positions in said elongated slot, and a cable line fixedly connected at one end thereof, to said knob with the other end of said cable line fixedly connected to the other end of said spring.

5. A toner dispensing device as claimed in claim 3, wherein said driving device further comprises a motor, a plurality of sprockets connected by a chain, and said special gear driven through a plurality of gears. said special gear. when engaged with said rack at the toothed portion thereof. being adapted to move said slidable plate in a direction to expand said spring with said slidable plate adapted to return to the original position thereof immediately when said toothless portion of said special gear reaches said rack to release engagement therebetween.

6. A toner dispensing device as claimed in claim 3. wherein said slidable plate is further provided with an elongated slot in the surface thereof to receive a stopping pin which extends outwardly at right angles from said guide plate. 

1. In a toner dispensing device for use in a developing apparatus of an electrostatic copying machine which comprises a dispenser casing retained in an opening formed on a wall of said developing apparatus, said dispensing casing having a slit formed in a bottom portion thereof, a container for toner powder removably received in and communicating with said dispenser casing, and a coil spring provided at the bottom of said dispenser casing above said slit with neighboring turns of said spring adapted to contact with each other in the contracted state of said spring, an improvement thereof for feeding toner powder uniformly and positively which comprises means for pulling one end of said spring for expansion thereof so that gaps are formed between said neighboring turns of said spring for toner powder to pass through said gaps and said slit, said pulling means being adapted to release pulling intermittently so as to allow said spring to be contracted with said neighboring turns thereof closed in order to suspend feeding of toner powder.
 2. A toner dispensing device as claimed in claim 1, wherein further comprises means for adjusting tension of said spring for adjusting intervals of gaps between said neighboring turns of said spring when said spring is pulled by said pulling means, and a driving device for said pulling means.
 3. A toner dispensing device as claimed in claim 1, wherein said pulling means further comprises a slidable plate slidably, reciprocatingly mounted on a guide plate fixed on a side wall of said developing apparatus, said slidable plate being provided with a rack which engages a special gear having a toothed portion and a toothless portion and which is driven by said driving device, and a cable line secured, at one end thereof, to said slidable plate with the other end of said cable line fixedly connected to said one end of said spring.
 4. A toner dispensing device as claimed in claim 1, wherein said tension adjusting means further comprises an adjusting plate with an elongated slot formed therein, and a knob which is slidable in said elongated slot and which can be fixed at desired positions in said elongated slot, and a cable line fixedly connected at one end thereof, to said knob with the other end of said cable line fixedly connected to the other end of said spring.
 5. A toner dispensing device as claimed in claim 3, wherein said driving device further comprises a motor, a plurality of sprockets connected by a chain, and said special gear driven through a plurality of gears, said special gear, when engaged with said rack at the toothed portion thereof, being adapted to move said slidable plate in a direction to expand said spring with said slidable plate adapted to return to the original position thereof immediately when said toothless portion of said special gear reaches said rack to release engagement therebetween.
 6. A toner dispensing device as claimed in claim 3, wherein said slidable plate is further provideD with an elongated slot in the surface thereof to receive a stopping pin which extends outwardly at right angles from said guide plate. 